In the context of this proposal, lethal bioynthesis may be defined as the conversion of substrate analogs by enzymes in a metabolic pathway to an antimetabolite. To ensure selectivity it is proposed that analogs of intermediates in the biosynthesis of selected vitamins, particularly of the B complex be prepared since a number of pathogenic bacteria biosynthesize B vitamins whereas the mammalian host generally does not possess the necessary enzymes to carry out the biosynthesis of this group of essential metabolites. The target compounds will be tested for anti-bacterial activity against E. coli.